Complementary metal-oxide-semiconductor (CMOS) technology continues to be an extremely important technology for the fabrication of integrated circuits. In CMOS technology, both p-type devices, such as p-type field-effect transistors, and n-type devices, such as n-type field effect transistors, are fabricated on a common semiconductor wafer.
Different processes or materials can be required in the fabrication of p-type devices and n-type devices. For example, forming p-type transistors and n-type transistors with matched threshold voltages can require the use of multiple different gate structure formation processes or work function layers, thereby increasing complexity and costs.